I was part of a road rage incident this morning. Sort of

I was driving to work early this morning (3:50), just leaving the I-12 split coming from Denham Springs and entering 1-10 going West. There was a white sports car in the far right lane and I was in the second lane from the right.
He was slightly swerving into my lane and then drove with his driver side wheels over the stripe for a while. I assumed he must be impaired, and beeped my horn to let him know I was about to pass him in my lane and that he should get over. Not laying on the horn mind you, but just 2 quick beeps.
Well, after I pass him, he switches lanes from the far right to the one adjacent to my left. At first I didn't think too much, but when I tried to slow down and let him get ahead of me, he slowed also. This went on for a while as he shadowed my every move. I looked over into his glass to see if I could perceive a driver, but it was dark and his tint was very dark, so I couldn't even see inside his car.
This is where I got somewhat concerned, imagining that he could have a gun pointed at me behind the glass and I'd be unaware.
I proceeded to step on the gas and kind of left him behind, but he also sped up and though he left a lane between us open, he was still basically shadowing me.
Fortunately, I turned to go towards North Baton Rouge and he continued straight towards the bridge, but it illustrates how quickly a problem can present itself without much forewarning.